Effect of exendin (exenatide)-GLP 1 receptor agonist on the thyroid and parathyroid gland in a rat model

C cell hypertrophy was elevated in exenatide-treated vs. untreated animals (22.5±8.7 vs. 10.5±2.7 cells/HPF). CEA staining failed to show effects by exendin. Calcitonin staining was significantly elevated in exenatide treated controls (P<0.001). Parathyroid glands were histologically normal in both groups, and serum calcium levels were within normal range in all animals. In summary, exenatide was associated with C cell hyperplasia and increased calcitonin staining of thyroids, but was unrelated to CEA levels. These data raise important concerns about the effects of exenatide which, given its wide clinical use, should be clarified with urgency.